What is Canonical URL?
Definition
A canonical URL is the preferred version of a web page that search engines should index and rank when identical or similar content exists at multiple URLs.
Why canonical url matters
Canonical URLs matter because the same content often appears at multiple URLs due to URL parameters, session IDs, sorting options, or site architecture. Without clear signals, search engines must guess which version to index, potentially splitting ranking signals across duplicates.
Proper canonicalization consolidates link equity to your preferred URL, ensuring all the authority built through backlinks benefits a single page rather than being diluted across variations.
Clear canonical signals also help search engines crawl your site more efficiently by indicating which URLs are worth indexing and which are duplicates.
Key concepts and types
- •Canonical tag
An HTML element (rel='canonical') that specifies the preferred URL for a page. - •Self-referencing canonicals
Pages that point to themselves as canonical, confirming they are the preferred version. - •Cross-domain canonicals
Canonical tags pointing to a different domain, used for syndicated or legitimately duplicated content. - •Canonical signals consolidation
How search engines combine hints from canonicals, redirects, internal links, and sitemaps. - •Canonical vs redirect
When to use canonical tags (multiple valid versions) vs 301 redirects (only one version should exist).
Common misconceptions
- ✕Canonical tags guarantee Google will respect your preference
- ✕Canonical tags are the same as 301 redirects
- ✕You should only use canonicals for exact duplicate content
- ✕Canonical tags prevent pages from being crawled
- ✕Self-referencing canonical tags are unnecessary
Related terms
FAQs
When should you use canonical tags vs 301 redirects?
Use canonical tags when you want both URLs accessible to users but consolidated for search engines. Use 301 redirects when only one URL should exist and users should be automatically sent there.
Do canonical tags pass link equity?
Yes, canonical tags consolidate link equity to the specified URL, though using 301 redirects is generally more reliable for passing link value.
Can you canonical to a page on a different domain?
Yes, cross-domain canonicals are valid for syndicated content, though search engines may not always honor them if content differs significantly.